Manufacturing method of semiconductor device and semiconductor device produced therewith

ABSTRACT

A semiconductor device (having an interlayer insulating film) which is sufficiently low in the dielectric constant and high in the mechanical strength is provided. 
     A manufacturing method of a semiconductor device includes: a step of forming a dielectric thin film in which a plurality of pores are arranged around a skeleton mainly made of a Si—O bond, on a surface of a semiconductor substrate on which a desired element region is formed; a step of applying patterning on a surface of the dielectric thin film through a mask; and a step of bringing a gas containing at least one kind of tetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS) molecules into contact with the patterned surface of the dielectric thin film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Division of application Ser. No. 11/661,706, filedMar. 1, 2007, which is a U.S. National Stage of PCT/JP2005/016031 filedSep. 1, 2005, which applications are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a manufacturing method of a semiconductordevice and a semiconductor device produced therewith, in particular, toa recovery technology of process damage in a dielectric thin film.

RELATED ART

In order to realize high speed/low power consumption of a semiconductordevice, it is very important to lower the dielectric constant of aninterlayer insulating film. In order to lower the dielectric constant,there have been proposed various devises. The inventors proposed adielectric thin film in which pores are regularly arranged (patentliterature 1).

Furthermore, as a modification method of a dielectric thin film, amethod where an organic silicon compound is brought into contact with adielectric thin film made of a Si—O bond to thermally treat withoutusing a metal catalyst to improve the hydrophobicity and the mechanicalstrength is proposed as well (patent literature 2).

Although a dielectric thin film like this is high in the pore rate andcan lower the dielectric constant, when it is actually used in asemiconductor device, various processes have to be undergone.Accordingly, even when a dielectric thin film high in the pore rate andlow in the dielectric constant can be formed, because of high pore rate,in subsequent various processes including a patterning process, in manycases, etching residue sticks to the inside of the pores, resulting incausing a rise in the dielectric constant or a deterioration in themechanical strength.

For instance, as an example of a technology by which a wiring structureis formed on a surface of a semiconductor substrate, there is atechnology called a damascene process.

An example of the damascene process will be described.

In the beginning, as shown in FIG. 27( a), on a surface of a siliconsubstrate 101 on which an element region is formed, as shown in FIG. 27(b), as an etching stopper 102, a silicon nitride (SiN) film having afilm thickness of substantially 50 nm is formed, and thereon, as shownin FIG. 27( c), as a low dielectric thin film 103, a porous silica filmis formed.

When a layer is formed, firstly, in a precursor solution obtained bydissolving a cationic cetyltrimethyl ammonium bromide (CTAB:C₁₆H₃₃N⁺(CH₃)₃Br⁻) as a surface active agent, tetraethoxy silane (TEOS)as a silica derivative and hydrochloric acid (HCl) as an acid catalystin a mixed solvent H₂O/alcohol, a substrate on which a first wiringlayer (not shown in the drawing) is formed is immersed and held at atemperature in the range of 30 to 150° C. for 1 to 120 hr to polymerizethe silica derivative due to a hydrolysis and polycondensation reaction(preliminary crosslinking step) to form a periodic self-agglomerate ofthe surface active agent. The substrate is pulled up, followed bywashing with water and drying, further followed by heating and calciningat 400° C. for 3 hr in air or a nitrogen atmosphere to completelypyrolyze and remove the surface active agent of a mold to form a puremesoporous silica thin film.

Thus obtained dielectric thin film 103 is patterned to form a contactpore. As shown in FIG. 28( d), as a anti-reflective layer 104, anorganic resin film is formed, followed by coating photoresist R1.

In the next place, as shown in FIG. 28( e), by photolithography, apattern is exposed, followed by developing to form a resist pattern R1.

Subsequently, as shown in FIG. 29( f), with the resist pattern R1 as amask, the dielectric thin film 103 is etched to form a wiring groove.

Further thereafter, as shown in FIG. 29( g), the resist pattern R1 andanti-reflective film 104 are asked to remove.

Subsequently, as shown in FIG. 30( h), a CF deposit film on a sidewallof the wiring groove due to the etching is removed, followed by washingwith an organic solvent to remove damage, and thereby a surface iscleansed.

Then, on a cleansed surface, by means of a PVD (Physical VaporDeposition) method, CVD (Chemical Vapor Deposition) method or ALD(Atomic Layer Deposition) method, as a diffusion inhibition barrier film105, a tantalum nitride (TaN) film, TaN/Ta laminate film, Ta film or WNfilm is formed, followed by forming a copper thin film as a seed film106 for copper plating (FIG. 30( i)).

Thereafter, as shown in FIG. 31( j), on the copper seed film 106, bymeans of the electroplating method, a copper plating layer as a wiringlayer 107 is formed.

Finally, as shown in FIG. 31( k), a surface is flattened by use of theCMP to polish and remove an excess copper plating layer and seed film106, followed by forming a wiring layer in the wiring groove, finally,as shown in FIG. 31( l), a SiN film 108 is formed as a cap film.

When a barrier layer is formed before the seed film 106 is formed, thebarrier layer 105 of a region from where the copper plating layer 107and the seed film (106) are polished and removed is removed as well.

Thus, a wiring structure having a flat surface can be obtained.

However, in actuality, the dielectric constant such as designed cannotbe obtained, resulting in, in some cases, causing a leakage current ordeteriorating the mechanical strength to make sufficient flattening dueto the CMP incapable.

From various experimental results, the inventors found the followings.

That is, even when such a mesoporous thin film is formed, immediatelyafter the film-forming, with effective characteristics as a dielectricthin film having sufficiently high mechanical strength and lowdielectric constant, in an actual production of a semiconductor device,various processes such as an etching process and a resist peelingprocess for patterning are necessary. Both in the etching process of thedielectric thin film and in the removing process of the resist, thedielectric thin film is exposed to a reactive atmosphere including anetching gas.

It is considered that, as a result, since the pore rate of the porousthin film that is formed with labor and high in the pore rate isdeteriorated and moisture tends to stick to a surface thereof,sufficient characteristics as an interlayer insulating film of asemiconductor device cannot be obtained.

Thus, damages are caused in the etching process of the dielectric thinfilm 103 (FIG. 29( f)) and the peeling process (asking process in FIG.29( g)) to deteriorate the dielectric thin film. Accordingly, thedielectric thin film is deteriorated and thereby the intrinsiccharacteristics thereof cannot be exerted.

Furthermore, the dielectric thin film is likely to be subjected todamages in various processes after the film-forming such as damages inorganic washing for removing the etching residue (FIG. 30( h)) and afterthe CMP process (FIG. 31( k)). Accordingly, there are problems indeterioration of the mechanical strength, peeling and resultantgeneration of leakage current.

While such a mesoporous thin film is high in the pore rate and low inthe dielectric constant, water and the like tend to intrude inside ofthe pores and contamination from a gaseous phase tends to occur.Accordingly, when it is used in an actual production of a semiconductordevice as an interlayer insulating film, as designed values of thedielectric constant and mechanical strength can be obtained only withdifficulty.

Patent literature 1: JP-A-2003-17482Patent literature 2: JP-A-2004-210579

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

As mentioned above, in an existing semiconductor manufacturing process,there are problems in that neither the dielectric constant of aninterlayer insulating film can be sufficiently lowered nor themechanical strength is sufficient.

Furthermore, as a semiconductor device is miniaturized, withoutrestricting to the damascene structure such as mentioned above, asurface is more and more flattened; accordingly, in many cases, the CMPresistance of a insulating film of the interlayer insulating film or thelike is a necessary condition. In order to sufficiently exert the CMPresistance, desired elastic modulus and hardness are necessary to becombined.

The invention has been made in view of the above-mentioned situationsand intends to provide a semiconductor device (provided with aninterlayer insulating film) sufficiently low in the dielectric constantand high in the mechanical strength.

Means for Solving the Problems

In this connection, a manufacturing method of a semiconductor device ofthe invention, comprising:

a step of forming a dielectric thin film in which a plurality of poresare arranged around a skeleton mainly made of a Si—O bond, on a surfaceof a semiconductor substrate on which a desired element region isformed;

a step of applying patterning on a surface of the dielectric thin filmthrough a mask; and

a step of bringing a gas containing at least one kind oftetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane (HMDS) andtrimethylchlorosilane (TMCS) molecules into contact with the patternedsurface of the dielectric thin film.

According to such a method, an insulating film can be formed by adielectric thin film in which a plurality of pores are arranged around askeleton mainly made of a Si—O bond. Accordingly, since the dielectricconstant of air is low, the dielectric constant can be largely loweredand, to process damages generated owing to the pores, when a gascontaining at least one kind of TMCTS, HMDS and TMCS molecules isbrought into contact, even when the process damages are inflicted,excellent recovery can be obtained. As a result, the extremely lowdielectric constant of an insulating film immediately after film-formingcan be maintained and thereby an insulating film high in the mechanicalstrength and high in the reliability can be obtained.

Furthermore, since damages inflicted in the resist asking process aswell can be recovered, not with a hard mask but with a resist mask apatterning step can be carried out, resulting in realizing low cost andan improvement in the patterning accuracy.

When damages are inflicted, such changes as Si—CH₃ bond →Si—OH bond,Si—H bond →Si—OH bond and Si—O—Si bond →2Si—OH bonds are caused, or,after once forming a radical, a Si—OH bond is generated, or, owing to awiring forming process, a site where H₂O is adsorbed is newly formed.

Thereby, the electric characteristics, the stability with time and thelike are considered deteriorated.

In this connection, since a process for recovery, that is, a recoveryprocess can be readily realized by substituting a gas in a chamber thatis used in the recovery process, the workability as well is excellent.That is, a Si—OH bond formed owing to the damages changes, due to therecovery process, to a Si—CH₃ bond, Si—O—Si bond or Si—H bond.Furthermore, when a Si—CH₃ bond or Si—O—Si bond is newly impartedthrough a Si—H bond or Si—OH bond, the electric characteristics and thestability with time can be improved.

Now, as applicable dielectric thin films, a porous silica film, zeolitefilm, HSQ film, MSQ film and the like can be cited. As forming methods,without restricting to a coating and calcining method, gas phasedeposition methods such as a CVD method and the like can be used. Forinstance, SiOC, SiOCH, SiCN and SiCO films are films obtained byrendering hydrophobic with silica derivatives such as TMCTS, HMDS, TMCSand the like as needs arise.

Silica derivatives that are used in the recovery process may be usedsingularly or continuously, simultaneously or alternatively in acombination of a plurality of kinds of silica derivatives.

Furthermore, when the TMCTS is used in the recovery process, not onlythe hydrophobicity and electric characteristics but also the mechanicalstrength and the interfacial adhesiveness can be improved.

Still furthermore, the recovery process is desirable to be a highconcentration, in particular, super critical TMCTS recovery treatment.This is same as well in a case of silica derivatives such as HMDS, TMCSor the like.

Furthermore, the TMCTS recovery treatment can be applied as well toprotection in the wiring forming process.

In addition, the recovery treatment may be, other than the thermalannealing, a plasma CVD treatment. Furthermore, when light irradiationis added, the reactivity can be more improved and the recovery effectcan be heightened.

Furthermore, since the formation under low temperatures can be applied,even when it is used as an interlayer insulating film of an integratedcircuit, without adversely affecting on an undercoat, an insulating filmhigh in the reliability can be formed. Since it can be formed withoutapplying a heating process of 500° C. or more, it can be applied evenwhen an aluminum wiring is used.

Still furthermore, since the dielectric thin film can be formed when aprecursor solution is fed followed by calcining, precise patternformation can be applied even to a miniature region. Accordingly, thereliability of the dielectric thin film can be improved.

Furthermore, when the concentration of the precursor solution iscontrolled, the pore rate can be appropriately controlled. Accordingly,insulator thin films having desired dielectric constant can be formedwith very good workability.

Accordingly, an insulating film having low capacitance can be readilyformed, the parasite capacitance can be reduced and a high-speedsemiconductor device can be obtained.

Now, a molecular formula of TMCTS (1,3,5,7-tetramethylcyclotetrasiloxane((SiH(CH₃))₄O₄) is as shown below.

Furthermore, a molecular formula of (hexamethyldisilazane((CH₃)₃SiNHSi(CH₃)₃) is as shown below.

Still furthermore, a molecular formula of TMCS (trimethylchlorosilane((CH₃)₃SiCl)) is as shown below.

Furthermore, In the manufacturing method of a semiconductor device ofthe invention,

the patterning step includes:

a step of forming a resist mask on the surface of the dielectric thinfilm obtained in the film-forming step; and

a step of etching the dielectric thin film through the resist mask.

According to the method, while including steps of generating damagessuch as an ashing step and the like, a recovery treatment is carriedout. Accordingly, the patterning step can be applied, without forming ahard mask, by use of the resist mask. As the result, a pattern can beformed with high transfer precision and less number of steps isnecessary for manufacture.

Furthermore, in the manufacturing method of a semiconductor device ofthe invention,

the patterning step includes:

a step of forming a hard mask on the surface of the dielectric thin filmobtained in the film-forming step;

a step of etching the dielectric thin film through the hard mask; and

before the step of etching the dielectric thin film, a step of peelingand removing a resist for the patterning of the hard mask.

According to the method, although the number of steps is increased,since the dielectric thin film can be inhibited from directly cominginto contact with the resist, the dielectric thin film can be inhibitedfrom deteriorating owing to the ashing.

Furthermore, the manufacturing method of a semiconductor device of theinvention, further comprising:

after the step of peeling and removing and before the step of etchingthe dielectric thin film, a step of bringing a gas containing at leastone kind of tetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane(HMDS) and trimethylchlorosilane (TMCS) molecules into contact.

Still furthermore, the manufacturing method of a semiconductor device ofthe invention, further comprising:

after the step of etching, a step of bringing a gas containing at leastone kind of tetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane(HMDS) and trimethylchlorosilane (TMCS) molecules into contact with thesurface of the dielectric thin film.

The hard mask may be used as it is as an insulating film of a device ormay be removed. When the hard mask is removed, even after the removalthereof, when the gas is brought into contact with a surface of thedielectric thin film therefrom the hard mask is removed, the recoveryproperty can be more improved.

Furthermore, In the manufacturing method of a semiconductor device ofthe invention,

the hard mask is a two-layer film, and

the manufacturing method comprising:

a step of asking the resist in a state that the hard mask on a lowerlayer side is remained; and

a step of etching the hard mask on the lower layer side by using thehard mask on an upper layer side as a mask.

According to the method, the number of steps increases. However, theresist can be assuredly inhibited from coming into contact directly withthe dielectric thin film and thereby the dielectric thin film can beinhibited from deteriorating owing to the asking. Furthermore, when thehard mask is made of a dielectric thin film, the hard mask, withoutremoving, can be used as it is as an insulating film.

Furthermore, In the manufacturing method of a semiconductor device ofthe invention, the patterning step is a step of forming a groove forforming a wiring, and

the patterning step includes:

a step of forming a conductive material layer in the groove; and

before the step of forming the conductive material layer,

a step of cleaning the surface of the dielectric thin film on which thegroove for forming the wiring is formed, and

a step of bringing a gas containing at least one kind oftetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane (HMDS) andtrimethylchlorosilane (TMCS) molecules into contact with the cleansedsurface of the dielectric thin film.

The step of cleaning intends to remove etching residue such as CF₄ andthe like. Other than organic cleaning, a dry process with plasma as wellcan be applied to cleanse.

Furthermore, In the manufacturing method of a semiconductor device ofthe invention,

the step of forming the conductive material layer includes:

a step of forming a seed layer for plating in the groove for forming thewiring;

a step of forming a plating layer by applying electroplating on the seedlayer; and

a step of removing the plating layer and the seed layer on thedielectric thin film by a CMP step.

According to the method, a damascene structure high in the reliabilitycan be formed. Before the seed layer is formed, a diffusion barrierlayer may be formed. The method is more effective in a case where acopper plating layer is used.

Furthermore, the manufacturing method of a semiconductor device of theinvention, further comprising:

after the removing step, a step of bringing a gas containing at leastone kind of tetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane(HMDS) and trimethylchlorosilane (TMCS) molecules into contact with thesurface of the dielectric thin film.

Furthermore, in the manufacturing method of a semiconductor device ofthe invention,

the patterning step is a step of forming a throughhole for forming acontact, and

the patterning step includes:

a step of forming a conductive material layer in the throughhole; and

before the step of forming the conductive material layer,

a step of applying organic cleaning on the surface of the dielectricthin film on which the throughhole is formed, and

a step of bringing a gas containing at least one kind oftetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane (HMDS) andtrimethylchlorosilane (TMCS) molecules into contact with the surface ofthe dielectric thin film to which the organic cleaning is applied.

The manufacturing method of a semiconductor device of the invention,further comprising:

before forming the mask, a step of bringing a gas containing at leastone kind of tetramethylcyclotetrasiloxane (TMCTS), hexamethyldisilazane(HMDS) and trimethylchlorosilane (TMCS) molecules into contact with thesurface of the formed dielectric thin film.

Furthermore, in the manufacturing method of a semiconductor device ofthe invention,

the step of forming the dielectric thin film includes:

a step of generating a precursor solution that contains a silicaderivative and a surface active agent, and has a composition ratio suchthat desired said pores are arranged;

a preliminary crosslinking step of increasing a temperature of theprecursor solution to start a crosslinking reaction;

a step of feeding the precursor solution in which the crosslinkingreaction is started in the preliminary crosslinking step on the surfaceof the semiconductor substrate; and

a step of calcining the semiconductor substrate that is brought intocontact with the precursor solution, and decomposing and removing thesurface active agent.

Still furthermore, the manufacturing method of a semiconductor device ofthe invention, further comprising:

a step of generating a precursor solution that contains a silicaderivative and a surface active agent, and has a composition ratio suchthat desired said pores are arranged;

a step of feeding the precursor solution on the surface of thesemiconductor substrate;

a preliminary crosslinking step of heating the semiconductor substratethat is brought into contact with the precursor solution, to start acrosslinking reaction; and

a step of calcining the semiconductor substrate, and decomposing andremoving the surface active agent.

Furthermore, in the manufacturing method of a semiconductor device ofthe invention, the feeding step is a step of immersing the semiconductorsubstrate in the precursor solution.

Still furthermore, in the manufacturing method of a semiconductor deviceof the invention,

the feeding step includes:

a step of immersing the semiconductor substrate in the precursorsolution and pulling the semiconductor substrate up at a desired speed.

Furthermore, in the manufacturing method of a semiconductor device ofthe invention, the feeding step is a step of coating the precursorsolution on the semiconductor substrate.

Still furthermore, in the manufacturing method of a semiconductor deviceof the invention, the feeing step is a rotary coating step of droppingthe precursor solution on the semiconductor substrate and rotating thesubstrate.

Furthermore, in the manufacturing method of a semiconductor device ofthe invention, the precursor solution allows the pores to beperiodically arranged. Alternatively, pores may be non-periodicallyarranged.

Still furthermore, a semiconductor device of the invention, comprising:

a dielectric thin film having contact pores formed by using the abovemethod; and

a conductive film filled in the contact pores.

In the semiconductor device of the invention, the conductive film filledin the contact pores of the dielectric thin film formed on a surface ofa semiconductor substrate is formed so as to come into contact with thesemiconductor substrate.

Furthermore, in the semiconductor device of the invention, thedielectric thin film is a porous silica thin film, and a copper thinfilm formed inside the contact pores constitutes a wiring layer.

Still furthermore, in the semiconductor device of the invention, theporous silica thin film has a thickness of 0.05 to 2 μm.

In the semiconductor device of the invention, the porous silica thinfilm has fine pores having a cubic structure, and at least a part of thefine pores is closed.

Furthermore, in the semiconductor device of the invention, the finepores are formed so as to have a wall distance of 0.2 to 2.5 nm.

ADVANTAGE OF THE INVENTION

According to the method of the invention, owing to the recoverytreatment, a high quality insulating film can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart diagram showing a process of an embodiment 1 ofthe invention,

FIG. 2 is a diagram showing a production process of a semiconductordevice of the embodiment 1 of the invention,

FIG. 3 is a diagram showing a production process of a semiconductordevice of the embodiment 1 of the invention,

FIG. 4 is a diagram showing a production process of a semiconductordevice of the embodiment 1 of the invention,

FIG. 5 is a diagram showing a production process of a semiconductordevice of the embodiment 1 of the invention,

FIG. 6 is a diagram showing a production process of a semiconductordevice of the embodiment 1 of the invention,

FIG. 7 is an explanatory diagram showing a recovery treatment step usedin an embodiment of the invention,

FIG. 8 is a diagram showing process kinds used in the embodiment of theinvention,

FIG. 9 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 10 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 11 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 12 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 13 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 14 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 15 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 16 is an explanatory diagram of an advantage due to the recoverytreatment used in the embodiment 1 of the invention,

FIG. 17 is a diagram showing a production process of a semiconductordevice of an embodiment 2 of the invention,

FIG. 18 is a diagram showing a production process of a semiconductordevice of an embodiment 2 of the invention,

FIG. 19 is a diagram showing a production process of a semiconductordevice of an embodiment 2 of the invention,

FIG. 20 is a diagram showing a production process of a semiconductordevice of an embodiment 2 of the invention,

FIG. 21 is a diagram showing a production process of a semiconductordevice of an embodiment 2 of the invention,

FIG. 22 is a diagram showing a production process of a semiconductordevice of an embodiment 3 of the invention,

FIG. 23 is a diagram showing a production process of a semiconductordevice of an embodiment 3 of the invention,

FIG. 24 is a diagram showing a production process of a semiconductordevice of an embodiment 3 of the invention,

FIG. 25 is a diagram showing a production process of a semiconductordevice of an embodiment 3 of the invention,

FIG. 26 is a diagram showing a production process of a semiconductordevice of an embodiment 3 of the invention,

FIG. 27 is a diagram showing a production process of a semiconductordevice of an existing example,

FIG. 28 is a diagram showing a production process of a semiconductordevice of an existing example,

FIG. 29 is a diagram showing a production process of a semiconductordevice of an existing example,

FIG. 30 is a diagram showing a production process of a semiconductordevice of an existing example and

FIG. 31 is a diagram showing a production process of a semiconductordevice of an existing example.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   -   101: silicon substrate    -   102: etching stopper layer    -   103: dielectric thin film    -   104: antireflective film    -   105: diffusion barrier film    -   106: seed film    -   107: copper plating film    -   108: cap film    -   201: silicon oxide film    -   202: silicon nitride film    -   203: silicon carbide film

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of a manufacturing method of the invention of asemiconductor device will be described in detail with reference to thedrawings. (Embodiment 1)

As an embodiment 1 of the invention, a manufacturing method of a singledamascene wiring structure in which the dielectric thin film is used asan interlayer insulating film of a semiconductor device will bedescribed.

-   -   The method, as shown in a flowchart in FIG. 1 and production        process diagrams shown in FIGS. 2( a) through 6(i), includes        recovery treatment steps (steps T107, T109, T111 and T115) of        forming an interlayer insulating film having a single damascene        wiring structure from a dielectric thin film made of a        mesoporous silica thin film and bringing into contact with TMCTS        molecules for every process to recover the process damage.

As the process, except only that, in the existing process, a recoverytreatment step for recovering the process damage is added to everyprocess, other processes are similar to that of the production processof a single damascene wiring structure shown in FIGS. 27 through 31.

FIG. 7 is a time chart of a recovery process used here. According to thetime chart, with nitrogen N₂ supplying, a temperature is raised fromroom temperature to 400° C. in 15 min, followed by keeping 400° C. for30 min with nitrogen flowing, further followed by stopping supplyingnitrogen, still further followed by vacuum suctioning to 0.4 Pa orbetter and keeping there for 20 min, followed by supplying a mixed gasof TMCTS/N₂. For a first 30 min, the mixed gas is supplied at 0.7 g/minand for a second 60 min it is supplied at 1.4 g/min. At this time,pressure is set at 24 kPa.

During the first supply step of nitrogen gas, a residual gas in achamber is replaced by nitrogen, followed by evacuating, furtherfollowed by supplying a mixed gas of TMCTS/N₂ to apply a recoverytreatment with the mixed gas of TMCTS/N₂ flowing.

In what follows, with reference to a flowchart of FIG. 1 and FIGS. 2( a)through 6(l), a formation process of an actual single damascene wiringstructure will be described.

In the beginning, as shown in FIG. 2( a), on a surface of a siliconsubstrate 101 provided with an element region, as shown in FIG. 2( b), asilicon nitride (SiN) film having a film thickness of substantially 50nm is formed as an etching stopper 102, and, on a top layer thereof, asshown in FIG. 2( c), a porous silica film is formed as a dielectric thinfilm 103 having low dielectric constant (FIG. 1: S101 and S102).

At the film-forming, same as so far, in a precursor solution obtained bydissolving cationic cetyltrimethylammonium bromide (CTAB:C₁₆H₃₃N⁺(CH₃)₃Br⁻) as a surface active agent, tetraethoxysilane (TEOS)as a silica derivative and hydrochloric acid (HCl) as an acid catalystin a mixed solvent of H₂O/alcohol, a substrate provided with a wiringlayer thereon (not shown in the drawing) is soaked and held there at atemperature in the range of 30 to 150° C. for 1 to 120 hr to polymerizethe silica derivative due to a hydrolysis and polycondensation reaction(preliminary crosslinking step) to form a periodical self-agglomerate ofthe surface active agent. The substrate is, after pulling up, washed anddried, followed by heating and calcining at 400° C. for 3 hr in air(nitrogen:oxygen=4: 1) to completely pyrolyze and remove the surfaceactive agent of a mold, thereby a pure mesoporous silica thin film isformed as a dielectric thin film 103.

At the time point, the TMCTS treatment described in the FIG. 7 isapplied to improve the resistant property of the film (FIG. 1: S103).

Thus, the obtained dielectric thin film 103 is patterned to form contactpores. As shown in FIG. 3( d), after an organic resin film is formed asan antireflective layer 104, a photoresist R1 is coated (FIG. 1: S104).

Subsequently, as shown in FIG. 3( e), pattern exposure due to thephotolithography and development are carried out to form a resistpattern R1 (FIG. 1: S105).

In the next place, with the resist pattern R1 as a mask, the dielectricthin film 103 is etched to form a wiring groove T (FIG. 1: S106).

Then, a treatment step shown in FIG. 7 is carried out to supply aprocessing gas containing TMCTS molecules on a surface including damagesdue to the etching of the dielectric thin film to apply the recoverytreatment to recover a sidewall of the groove (FIG. 4( f), FIG. 1:T107).

Subsequently, the resist pattern R1 is asked to remove and theantireflective film 104 is etched to remove (FIG. 1: A108).

The treatment step shown in FIG. 7 is once more applied to supply aprocessing gas containing TMCTS molecules on a surface containingdamages due to the asking of the resist pattern R1 to apply the recoverytreatment (FIG. 4( g): T109).

Subsequently, a CF deposit film on a sidewall of the wiring groove dueto the etching is removed, an organic solvent is used to wash to removedamages, thereby a surface is cleansed (FIG. 1: S110).

Furthermore, the treatment step shown in FIG. 7 is applied to supply aprocessing gas containing TMCTS molecules on a surface containingdamages due to the cleaning with an organic solvent to carry out therecovery treatment (FIG. 5( h), FIG. 1: T111).

Then, on the cleansed surface, by means of the PVD, CVD or the likemethod, tantalum nitride (TaN) as a diffusion inhibition barrier film105 and a copper thin film as a seed film 106 for copper plating areformed (FIG. 5( i)) (FIG. 1: S112).

Subsequently, as shown in FIG. 6( j), by means of the electroplatingmethod, on the Cu seed layer, a copper plating layer is formed as awiring layer 107 (FIG. 1: S113).

At the last, the surface is flattened by the CMP to polish and removeexcess copper plating layer and seed film 106 (FIG. 1: S114).

Furthermore, the treatment step shown in FIG. 7 is applied to supply aprocessing gas containing TMCTS molecules on a surface containingdamages due to the CMP to carry out the recovery treatment (FIG. 6( k),FIG. 1: T115).

At the last, a wiring layer is formed in the wiring groove, followed byforming, as shown in FIG. 6( l), a SiN film as a cap film, furtherfollowed by evaluating the characteristics (FIG. 1: S116).

Since the dielectric constant substantially as designed can be thusobtained, a wiring structure small in the parasite capacitance, freefrom the leakage current, high in the reliability and having a flatsurface can be obtained.

Furthermore, when the damages due to the respective processes arerecovered by the recovery treatment, the patterning can be applied, notwith the hard mask but with direct use of the resist pattern, with thecharacteristics maintained sufficiently. Accordingly, more precisepatterning can be obtained.

Still furthermore, since the dielectric thin film sufficiently high inthe mechanical strength can be obtained, the CMP can be applied tosufficiently flatten.

In the next place, results of experiments carried out for verifyingadvantages of the recovery treatment will be shown.

FIG. 8 is a correspondence table between signs and treatments that showthe respective treatment steps.

In the beginning, measurements of thickness variations after therespective treatments will be described.

(On Film Thickness Variation)

As shown in FIG. 9, an average value of film thicknesses of dielectricthin films 103 after the step of FIG. 2( c) where the TMCTS treatment isapplied immediately after the film-forming as a reference was 327 nm.

As the ashing process, three kinds, that is, the CF₄/O₂ ashing followedby O₂ ashing as shown by A1 in FIG. 8, the CF₄/O₂ ashing as shown by A2and the O₂ ashing as shown by A3 are carried out. After the respectiveashing processes, the recovery treatment (T) with TMCTS molecules suchas shown in FIG. 7 is applied. Results are shown with A1+T, A2+T andA3+T.

As the results, it is found that although the film thicknesses arelowered by substantially 10% due to the CF₄/O₂ ashing process (A1, A2),ones after the recovery treatment, which are shown by the A1+T and A2+T,are only slightly increased in the film thickness.

Furthermore, it is found that, although in the O₂ ashing process (A3),the film thickness is hardly damaged, one after the recovery treatment,which is shown by A3+T, is slightly reduced in the film thickness.

In the next place, an affect of the organic cleaning treatment (WC) onthe film thickness was measured as well.

From the results, it is found that although the film thickness is hardlyaffected by the organic cleaning treatment, one after the recoverytreatment, which is shown by WC+T, is slightly reduced in the filmthickness.

Furthermore, one in a state after the treatment in a half-etching stepwith Ar/C₅F₈/O₂ is shown by HE and shows a reduction in the filmthickness. However, one after the recovery treatment shown by the HE+Tis only slightly reduced in the film thickness.

(On Variation of Refractive Index)

In the next place, measurements of the refractive index are shown inFIG. 10.

As shown in FIG. 10, the refractive index of a dielectric thin film 103after the step shown by FIG. 2( c) where the TMCTS treatment is appliedimmediately after the film-forming as a reference was 1.202.

Similarly to the ashing process, three kinds, that is, the CF₄/O₂ ashingfollowed by O₂ ashing as shown by A1 in FIG. 8, the CF₄/O₂ ashing asshown by A2 and the O₂ ashing as shown by A3 were carried out. After therespective ashing steps, the recovery treatment (T) with TMCTS moleculessuch as shown in FIG. 7 was applied. Results are shown with A1+T, A2+Tand A3+T.

As the result, it is found that although the refractive index is reduceddue to the CF₄/O₂ ashing (A1, A2), ones after the recovery treatmentsshown by A1+T and A2+T show an increase in the refractive index, thatis, owing to inclusion of the TMCTS, the film density is increased.

Furthermore, in the O₂ ashing (A3), the refractive index is increasedrelative to the film thickness. This is considered due to deteriorationof the hydrophobicity. One after the recovery treatment shown by A3+Tshows a further increase in the refractive index.

Still furthermore, an affect of the organic cleaning treatment (WC) onthe refractive index was measured as well.

As the result, it is found that neither one after the organic cleaningtreatment nor one further followed by the recovery treatment shown byWC+T show variation in the refractive index.

Furthermore, one in a state after the treatment in a half-etching stepwith Ar/C₅F₈/O₂ is shown with a mark HE. Neither one in this state norone after the recovery treatment shown by HE+T hardly show variation inthe refractive index.

(On Variation of Dielectric Constant (k Value))

In the next place, measurements of the dielectric constant are shown inFIG. 11.

As shown in FIG. 11, the dielectric constant of a dielectric thin film103 after the step shown by FIG. 2( c) where the TMCTS treatment isapplied immediately after the film-forming as a reference was 2.35 inair and 2.19 in a nitrogen atmosphere. Left sides in FIG. 11 showmeasurement values in air and right sides therein show measurementvalues in a nitrogen atmosphere.

Similarly to the ashing process, three kinds, that is, the CF₄/O₂ ashingfollowed by O₂ ashing as shown by A1 in FIG. 8, the CF₄/O₂ ashing asshown by A2 and the O₂ ashing as shown by A3 were carried out. After therespective ashing processes, the recovery treatment (T) with TMCTSmolecules such as shown in FIG. 7 was applied. Results are shown withA1+T, A2+T and A3+T.

The k values are, though deteriorated in the respective processes,largely recovered due to the recovery treatment. In the organic cleaningand half-etching, the k values are recovered to an initial value or lessby the recovery treatment.

That is, it is found that, as the variation rates of the dielectricconstant are shown in FIG. 12, the dielectric constant increase in therange of 9 to 28% due to the respective ashing processes (A1, A2, A3),by 9% due to the organic cleaning (WC) and by 4% due to the HE. However,ones after the recovery treatment shown by A1+T, A2+T and A3+T showrecovery in the range of 23 to 68%.

(In-plane Distribution)

In the next place, the in-plane distribution of the dielectric constantof each of the dielectric thin films is measured and results are shownin FIGS. 13( a) and 13(b). FIG. 13( a) shows the dielectric constant (kvalue) after the respective treatments, FIG. 13( b) shows the dielectricconstant (k value) after the recovery treatment, and horizontal axes inFIGS. 13( a) and 13(b) show a distance (mm) from a wafer center.

It is found that there is no remarkable axis direction dependency(in-plane distribution) in deteriorations of the k values after therespective processes and, in the ashing treatments A1 and A3 includingthe O₂ ashing, a wafer edge portion is less deteriorated.

(Leakage Current)

In the next place, a leakage current of each of the dielectric thinfilms was measured and results are shown in FIGS. 14( a) and 14(b). FIG.14( a) shows the leakage currents after the respective treatments, FIG.14( b) shows the leakage currents after the recovery treatment, andhorizontal axes in FIGS. 14( a) and 14(b) show a magnitude of anelectric field (MV/cm).

In the case of the organic cleaning, the leakage current issubstantially same, that is, does not deteriorate. However, in theasking processes (A1, A2, A3) and the HE process, the leakage currentincreases. When the recovery treatment (T) is applied thereto, as shownby A1+T, A2+T and A3+T, a large recovery is found.

(Elastic Modulus, Hardness)

In the next place, the elastic modulus and hardness of each of thedielectric thin films are measured and results are shown in FIGS. 15( a)and 15(b).

In FIGS. 15( a) and 15(b), measurements of rates of change of theelastic modulus (E value) and hardness (H value) after the respectivetreatments and the recovery treatment are shown. FIG. 15( c) shows therespective measured data.

(Relationship between Hardness, Elastic Modulus and Dielectric Constant)

In the next place, in order to obtain the relationship between thehardness, elastic modulus and dielectric constant of the dielectric thinfilms, the relationships between the hardness, elastic modulus anddielectric constant of the dielectric thin films were measured andresults are shown in FIGS. 16( a) and 16(b).

In FIG. 16( b), ones of which k values are smaller than a straight lineof Ew=17.5 GPa corresponding to the elastic modulus and k value of thedielectric thin film immediately after the film-forming, that is, oneslocated on a left side are improved films. As obvious from the drawing,it is found that ones after the recovery treatment all are present on aleft side and exert excellent characteristics.

Embodiment 2

In the embodiment 1, a production process of a semiconductor device,which contains a step where a groove is formed in an interlayerinsulating film with a resist pattern as a mask was described. In thepresent embodiment, formation of a groove by use of a hard mask having atwo-layered structure will be described. In the embodiment as well,similarly, a manufacturing method of a single damascene wiring structurewill be described.

The method is similar to one that is described in the embodiment 1 onlyexcept that, as production process charts are shown in FIGS. 17( a)through 21(n), as a hard mask, a two-layer structure mask made of asilicon oxide film 201 and a silicon nitride film 202 is used. In themethod, an interlayer insulating film of the single damascene wiringstructure is formed of a dielectric thin film made of a mesoporoussilica thin film and an individual process includes a recovery treatmentwhere TMCTS molecules are brought into contact to recover the processdamages.

In the embodiment, since a two-layer structure hard mask is used, stepswhere the dielectric thin film is exposed and damaged are etching thedielectric thin film itself (FIG. 20( i)) and an organic cleaning stepafter the etching (FIG. 20( j)). Accordingly, in the embodiment, afterthe two steps, a recovery treatment is carried out. The recovery processis carried out according to a time chart shown in FIG. 7.

In what follows, with reference to FIGS. 17( a) through 21(n), forming asingle damascene wiring structure that uses a two-layer structure hardmask will be described.

In the beginning, as shown in FIGS. 17( a) through 17(c), similarly tothe embodiment 1, on a surface of a silicon substrate 101 on which anelement region is formed, a silicon nitride (SiN) film having a filmthickness of substantially 50 nm is formed as an etching stopper 102,followed by forming thereon a porous silica thin film as a lowdielectric constant dielectric thin film 103.

Subsequently, as shown in FIG. 17( d), a silicon oxide film 201 and asilicon nitride film 202 are formed by means of the CVD method to form atwo-layer structure hard mask.

After that, similarly, as shown in FIG. 18( e), an organic resin film isformed as an antireflective film 104, followed by coating a photoresistR1.

Subsequently, as shown in FIG. 18( f), similarly to the embodiment 1, byuse of the photolithography, pattern exposure and development areapplied to form a resist pattern R1.

After that, as shown in FIG. 19( g), with the silicon oxide film 201that is a first layer hard mask remained, only the antireflective film104 and silicon nitride film 202 are patterned.

Subsequently, as shown in FIG. 19( h), with the silicon oxide film 201remained, the resist pattern R1 is removed by means of the O₂ ashing. Atthis time, the dielectric thin film 103 does not come into contact withO₂ plasma; accordingly, it is hardly damaged. However, in some cases,the dielectric thin film 103 is slightly damaged through the siliconoxide film 201. Accordingly, it is desirable to apply the recoverytreatment shown in FIG. 7 after the ashing.

After that, the silicon oxide film 201 that is a hard mask on a lowerlayer side and the dielectric thin film 103 are continuously etched.Subsequently, the treatment step shown in FIG. 7 is applied to supply aprocessing gas containing the TMCTS molecules on a surface containingdamages due to the etching of the dielectric thin film to apply therecovery treatment to recover a groove sidewall (FIG. 20( i)).

Subsequently, a CF deposit film on a sidewall of the wiring groove dueto the etching is removed, a cleaning step is applied with an organicsolvent to remove damages to cleanse a surface, the treatment step shownin FIG. 7 is further applied to supply a processing gas containing theTMCTS molecules on a surface containing damages due to the washing withan organic solvent to apply the recovery treatment step (FIG. 20( j)).

In the next place, on a cleansed surface, by means of the PVD method orCVD method, as a diffusion inhibition barrier film 105, tantalum nitride(TaN) is formed, followed by forming a copper thin film as a seed layer106 for copper plating (FIG. 20 (k)).

Steps after that are similar to the embodiment 1 except that on a toplayer of a dielectric thin film 103 a silicon oxide film 201 and asilicon nitride film 202 that are used as a hard mask remain in astacked state.

After the respective treatment steps are thus carried out, through stepsof FIGS. 21( l) through 21(n), a wiring layer is formed in a wiringgroove, followed by finally forming a SiN film as a cap film, furtherfollowed by evaluating the characteristics.

Thus, the dielectric constant substantially as designed can be obtained.Accordingly, a wiring structure sufficiently small in the parasitecapacitance, free from the leakage current, high in the reliability andhaving a flat surface can be obtained.

In the embodiment 2, a hard mask with a two-layer structure is used;accordingly, the process damage is a little small.

Embodiment 3

In the embodiment 2, a manufacturing step of a semiconductor device,which contains a step where a groove is formed in an interlayerinsulating film with a two-layer structure hard mask as a mask wasdescribed. In the present embodiment, formation of a groove with asingle-layer hard mask will be described. In the embodiment as well,similarly, a manufacturing method of a single damascene wiring structurewill be described.

The method is similar to that described in the embodiment 2 only exceptthat, as production process charts are shown in FIGS. 22( a) through26(n), as a hard mask, a silicon carbide film 301 is used. In themethod, an interlayer insulating film having the single damascene wiringstructure is formed of a dielectric thin film made of a mesoporoussilica thin film and an individual process includes a recovery treatmentstep where the dielectric thin film is brought into contact with TMCTSmolecules to recover the process damages.

In the embodiment, a single layer structure hard mask is used.Accordingly, in comparison with a case where the two-layer structurehard mask is used, the dielectric thin film is exposed in the ashingstep of the resist pattern (FIG. 24( h)), resulting in an increase insteps where damages are caused. As the result, after the ashing step ofthe resist pattern as well, a recovery treatment step becomes necessary.Still furthermore, after that, similarly to the embodiment 2, the stepsin which damage is given are an etching step of the dielectric thin filmitself (FIG. 25( j) and an organic cleaning step after the etching (FIG.25( k)), and after the two steps the recovery treatment step is carriedout. Furthermore, the recovery step is carried out according to the timechart shown in FIG. 7.

In what follows, with reference to FIGS. 22( a) through 26(n), forming asingle damascene wiring structure with a single layer structure hardmask will be described.

In the beginning, as shown in FIGS. 22( a) through 22(c), similarly tothe embodiments 1 and 2, on a surface of a silicon substrate 101 onwhich an element region is formed, a silicon nitride (SiN) film having afilm thickness of substantially 40 nm is formed as an etching stopper102, followed by forming thereon a porous silica thin film as a lowdielectric constant dielectric thin film 103.

Subsequently, as shown in FIG. 22( d), a silicon carbide film (SiC) 301is formed by means of the CVD method to form a single-layer structurehard mask. As the materials of the hard mask, other than SiC, SiOC, SiOor the like can be applied.

After that, similarly, as shown in FIG. 23( e), an organic resin film isformed as an antireflective film 104, followed by coating a photoresistR1.

Subsequently, as shown in FIG. 23( f), similarly to the embodiments 1and 2, by use of the photolithography, pattern exposure and developmentsteps are applied to form a resist pattern R1.

After that, as shown in FIG. 24( g), the antireflective film 104 andsilicon carbide film 301 that is a mask are patterned.

Subsequently, the resist pattern R1 is removed by means of the O₂ashing. At this time, a surface of the dielectric thin film is damageddue to O₂ plasma; accordingly, it is desirable to apply the recoverytreatment shown in FIG. 7 after the ashing (FIG. 24( h)).

After that, the dielectric thin film 103 is etched. Subsequently, thetreatment step shown in FIG. 7 is applied to supply a processing gascontaining the TMCTS molecules on a surface containing damages due tothe etching of the dielectric thin film to apply recovery treatment torecover a groove sidewall (FIG. 25( i)).

Subsequently, a CF deposit film on a sidewall of the wiring groove dueto the etching process is removed, an organic solvent is used to wash toremove damages to cleanse the surface, the treatment step shown in FIG.7 is further applied to supply a processing gas containing the TMCTSmolecules on a surface containing damages due to the washing with anorganic solvent to apply a recovery treatment (FIG. 25( j)).

In the next place, on a cleansed surface, by means of the PVD method orCVD method, as a diffusion inhibition barrier film 105, tantalum nitride(TaN) is formed, followed by forming a copper thin film as a seed film106 for copper plating (FIG. 25( k)).

Steps after that are similar to the embodiments 1 and 2 except that (asshown in FIGS. 26( l) through 26(n)) on a top layer of the dielectricthin film 103, a silicon carbide film 301 that is used as a hard maskremains in a stacked state.

After the respective treatment steps are thus carried out, a wiringlayer is formed in a wiring groove, followed by finally forming a SiNfilm as a cap film, further followed by evaluating the characteristics.

Thus, the dielectric constant substantially as designed can be obtained.Accordingly, a wiring structure sufficiently small in the parasitecapacitance, free from the leakage current, high in the reliability andhaving a flat surface can be obtained.

In the embodiment, a hard mask with a single-layer structure is used;accordingly, the process damage is a little larger than that of the hardmask with a two-layer structure hard mask. However, the damages can berecovered by the recovery treatment.

The composition of the precursor solution is not restricted to that ofthe embodiments. Relative to a solvent of 100, a surface active agent, asilica derivative and an acid oxide, respectively, are desirablycontained in the range of 0.01 to 0.1, 0.01 to 0.5 and 0 to 5. When aprecursor solution having such a composition is used, a low dielectricconstant insulating film having cylindrical pores can be formed.

Furthermore, in the embodiment, as a surface active agent, a cationiccetyltrimethylammonium bromide (CTAB: C₁₆H₃₃N⁺(CH₃)₃Br⁻) was used.However, it goes without saying that, without restricting thereto, othersurface active agents may be used.

However, when, as a catalyst, an alkali ion such as Na ion is used, asemiconductor material is deteriorated. Accordingly, it is desirable touse a cationic surface active agent and an acid catalyst as a catalyst.As the acid catalysts, other than HCl, nitric acid (HNO₃), sulfuric acid(H₂SO₄), phosphoric acid (H₃PO₄), H₄SO₄ or the like may be used.Alternatively, a nonionic surface active agent may be used.

As the silica derivatives, without restricting to TEOS, siliconalkoxides such as tetramethoxysilane (TMOS) or the like can be desirablyused.

Furthermore, as the solvent, a mixed solvent, water/alcohol, was used.However, water can be used alone.

Still furthermore, as a sintering atmosphere, an air atmosphere wasused. However, reduced pressure atmosphere or a nitrogen atmosphere canbe used. It is desirable to use a forming gas made of a gas mixture ofnitrogen and hydrogen. In that case, since the moisture resistance isimproved or microscopic electrical defects of the film are remedied, theleakage current can be reduced.

Furthermore, a blending ratio of a surface active agent, silicaderivative, acid catalyst and solvent can be appropriately varied.

A preliminary polymerization step was carried out at a temperature inthe range of 30 to 150° C. for a holding time in the range of 1 to 120hr. However, it is desirable for the temperature to be set in the rangeof 60 to 120° C. and more desirably at 90° C.

Furthermore, the sintering step was set at 400° C. and 1 hr. However, itmay be set in the range of substantially 300 to 500° C. and for 1 to 5hr. It is desirably set in the range of 350 to 450° C.

In the embodiment, a spinner was used to coat. However, a brush coatingmethod that uses a brush to coat may be applied.

The recovery treatment can be applied as well to, other than the poroussilica film, films such as a zeolite film, HSQ film, MSQ film or onethat is rendered hydrophobic as needs arise with a silica derivativesuch as TMCTS, HMDS, TMCS or the like.

The recovery treatment can be applied to etching processes such as anacid type, organic acid type, chlorine type, wet type, dry type or thelike.

In addition to the above, in the embodiment, an interlayer insulatingfilm that is used in a single damascene wiring structure was described.It goes without saying that the invention can be applied as well to amultilayer wiring structure that uses an aluminum wiring.

Furthermore, the dielectric thin film used in the invention is adielectric thin film that is mainly made of Si—O bonds and may partiallycontain an organic element. Except that being made of Si—O bonds meansbeing made of a structure where at least two O atoms are bonded to oneSi atom and through the O atoms other Si atoms are bonded, there is noparticular restriction. For instance, a hydrogen atom, halogen atom,alkyl group, phenyl group or a functional group containing these may bepartially bonded to a silicon atom.

A ratio of Si to O in the dielectric thin film can be confirmed by meansof elemental analysis with XPS and is preferably in the range of0.5≦Si/O (atomic ratio)≦1.0 and a weight ratio of Si therein ispreferably 40% by weight or more. Furthermore, a Si—O bond can beconfirmed by use of the IR. As general ones, thin films made of silica,hydrogenated silsesquioxane, methyl silsequioxane, hydrogenated methylsilsesquioxane, dimethylsiloxane and the like can be cited.

Furthermore, a surface of the dielectric thin film of the invention maybe treated in advance with a well known surface active agent including amethyl group, hydrogen group or the like. For instance, a dielectricthin film treated with hexamethyldisilazane (HMDS),trimethylsilylchloride (TMSC), monosilane or the like can be used aswell.

The dielectric thin film that is used in the invention preferably hasmeso-pores. Furthermore, an average pore diameter is preferably in therange of 0.5 to 10 nm. When the pore diameter is in this range, owing toa treatment described below, sufficient mechanical strength and lowdielectric constant can be achieved in combination.

In general, an average pore diameter of a thin film can be measured byuse of a 3-sample system of a full automatic gas adsorption apparatus(trade name: Autosorb-3B, manufactured by Quantachrome Instruments). Inthe measurement at this time, a nitrogen absorption method is carriedout under a liquid nitrogen temperature (77K), a specific surface areacan be obtained by means of the BET method, and a pore distribution canbe obtained by the BJH method.

The dielectric thin films used in the invention are not particularlyrestricted as far as these are above-mentioned ones. These can beclassified according to manufacturing methods thereof. That is, (1) athin film obtained by film-forming alkoxysilane by a sol-gel methodfollowed by rendering porous, (2) a thin film obtained byself-organizing silica sol and an organic compound, followed by removingthe organic compound after film-forming to make porous, and (3) a thinfilm obtained by growing zeolite crystal on a surface of a substrate torender porous can be cited.

Dielectric thin films used in the manufacturing method will be describedbelow.

(1) Thin Film Obtained by Film-Forming Alkoxysilane by a Sol-Gel MethodFollowed by Rendering Porous

In the method, in order to obtain a porous thin film, a manufacturingmethod thereof is not particularly restricted. However, specifically,the porous thin film can be manufactured as shown in examples below.

In the beginning, a coating solution for film-forming is prepared. Thecoating solution can be obtained by adding alkoxysilane and a catalystthat are components respectively described below, and water, and asneeds arise, a solvent, followed by agitating at a temperature in therange of 0 to 70° C., preferably in the range of 30 to 50° C. forseveral minutes to 5 hours, preferably for 1 to 3 hr. In the beginning,the respective components will be described.

(Alkoxysilane)

The alkoxysilane that is used in the production of the dielectric thinfilm is not particularly restricted. Specific examples thereof includetetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane,tetraisopropoxysilane, tetrabutoxysilane and the like;trialkoxyfluorosilanes such as trimethoxyfluorosilane,triethoxyfluorosilane, triisopropoxyfluorosilane, tributhoxyfluorosilaneand the like; fluorine-containing alkoxysilanes such as CF₃(CF₂)₃CH₂CH₂Si(OCH₃)₃, CF₃ (CF₂)₅CH₂CH₂Si(OCH₃)₃, CF₃(CF₂)₇CH₂CH₂Si(OCH₃)₃, CF₃(CF₂)₉CH₂CH₂Si(OCH₃)₃,(CF₃)₂CF(CF₂)₄CH₂CH₂Si(OCH₃)₃, (CF₃)₂CF(CF₂)₆CH₂CH₂Si(OCH₃)₃,(CF₃)₂CF(CF₂)₈CH₂CH₂Si(OCH₃)₃, CF₃ (C₆H₄)CH₂CH₂Si(OCH₃)₃, CF₃(CF₂)₃(C₆H₄) CH₂CH₂Si(OCH₃)₃, CF₃ (CF₂)₅ (C₆H₄)CH₂CH₂Si(OCH₃)₃, CF₃(CF₂)₇ (C₆H₄)CH₂CH₂Si(OCH₃)₃, CF₃(CF₂)₃CH₂CH₂SiCH₃ (OCH₃)₂,CF₃(CF₂)₅CH₂CH₂SiCH₃ (OCH₃)₂, CF₃ (CF₂)₇CH₂CH₂SiCH₃ (OCH₃)₂, CF₃(CF₂)₉CH₂CH₂SiCH₃ (OCH₃)₂, (CF₃)₂CF(CF₂)₄CH₂CH₂SiCH₃ (OCH₃)₂, (CF₃)₂CF(CF₂)₆CH₂CH₂SiCH₃ (OCH₃)₂, (CF₃)₂CF (CF₂)₈CH₂CH₂SiCH₃ (OCH₃)₂, CF₃(C₆H₄)CH₂CH₂SiCH₃ (OCH₃)₂, CF₃ (CF₂)₃ (C₆H₄)CH₂CH₂SiCH₃ (OCH₃)₂, CF₃(CF₂)₅ (C₆H₄)CH₂CH₂SiCH₃(OCH₃)₂, CF₃ (CF₂)₇ (C₁₋₆H₄)CH₂CH₂SiCH₃(OCH₃)₂,CF₃ (CF₂)₃CH₂CH₂Si(OCH₂CH₃)₃, CF₃(CF₂)₅CH₂CH₂Si(OCH₂CH₃)₃, CF₃(CF₂)₇CH₂CH₂Si(OCH₂CH₃)₃, CF₃ (CF₂)₉CH₂CH₂Si(OCH₂CH₃)₃ and the like;trialkoxyalkylsilanes such as trimethoxymethylsilane,triethoxymethylsilane, trimethoxyethylsilane, triethoxyethylsilane,trimethoxypropylsilane, triethoxypropylsilane and the like;trialkoxyarylsilanes such as trimethoxyphenylsilane,triethoxyphenylsilane, trimethoxychlorophenylsilane,triethoxychlorophenylsilane and the like; trialkoxyphenethylsilanes suchas trimethoxyphenethylsilane, triethoxyphenethylsilane and the like; anddialkoxyalkylsilanes such as dimethoxydimethylsilane,diethoxydimethylsilane and the like. Among these, tetraethyoxysilane canbe preferably used.

The alkoxysilanes can be used singularly or in a combination of at leasttwo kinds thereof.

(Catalyst)

As a catalyst used for the preparation of a coating solution, at leastone kind selected from an acid catalyst or an alkali catalyst can beused.

Examples of the acid catalysts include an inorganic acid and an organicacid. Examples of the inorganic acids include hydrochloric acid, nitricacid, sulfuric acid, fluoric acid, phosphoric acid, boric acid,hydrobromic acid and the like. Meanwhile, examples of the organic acidsinclude acetic acid, propionic acid, butanoic acid, pentanoic acid,hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoicacid, oxalic acid, maleic acid, methylmalonic acid, adipic acid, sebacicacid, gallic acid, butyric acid, mellitic acid, arachidonic acid,shikimic acid, 2-ethylhexanoic acid, oleic acid, stearic acid, linoleicacid, linolenic acid, salicylic acid, benzoic acid, p-aminobenzoic acid,p-toluenesulfonic acid, benzenesulfonic acid, monochloroacetic acid,dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, formicacid, malonic acid, sulfonic acid, phthalic acid, fumaric acid, citricacid, tartaric acid, succinic acid, fumaric acid, itaconic acid,mesaconic acid, citraconic acid, malic acid and the like.

Examples of the alkali catalysts include ammonium salts andnitrogen-containing compounds. Examples of ammonium salts includetetramethylammonium hydroxide, tetraethylammonium hydroxide,tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and thelike. Examples of nitrogen-containing compounds include pyridine,pyrrol, piperidine, 1-methylpiperidine, 2-methylpiperidine,3-methylpiperidine, 4-methylpiperidine, piperazine, 1-methylpiperazine,2-methylpiperazine, 1,4-dimethylpiperazine, pyrrolidine,1-methylpyrrolidine, picoline, monoethanolamine, diethanolamine,dimethyl monoethanolamine, monomethyl diethanolamine, triethanolamine,diazabicyclooctane, diazabicyclononane, diazabicycloundecene,2-pyrazoline, 3-pyrroline, quinuclidine, ammonia, methylamine,ethylamine, propylamine, butylamine, N,N-dimethylamine,N,N-diethylamine, N,N-dipropylamine, N,N-dibutylamine, trimethylamine,triethylamine, tripropylamine, tributylamine and the like.

(Solvent)

Examples of solvents that can be used for the preparation of a coatingsolution include mono-alcohol solvents such as methanol, ethanol,n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol,n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol,3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol,2-ethylbutanol, sec-heptanol, heptanol-3, n-octanol, 2-ethylhexanol,sec-octanol, n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol,sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol,sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol,3,3,5-trimethylcyclohexanol, benzyl alcohol, phenylmethyl carbinol,diacetone alcohol, cresol and the like; polyhydric alcohol solvents suchas ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol,pentanediol-2,4,2-methylpentanediol-2,4, hexanediol-2,5,heptanediol-2,4,2-ethylhexanediol-1,3, diethylene glycol, dipropyleneglycol, triethylene glycol, tripropylene glycol, glycerine and the like;ketone solvents such as acetone, methyl ethyl ketone, methyl-n-propylketone, methyl-n-butyl ketone, diethyl ketone, methyl-i-butyl ketone,methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone,di-i-butyl ketone, trimethylnonanone, cyclohexanone, 2-hexanone,methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetonealcohol, acetophenone, fenthion and the like; ether solvents such asethyl ether, i-propyl ether, n-butyl ether, n-hexyl ether, 2-ethylhexylether, ethylene oxide, 1,2-propylene oxide, dioxolane,4-methyldioxolane, dioxane, dimethyldioxane, ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether,ethylene glycol mono-n-butyl ether, ethylene glycol mono-n-hexyl ether,ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutylether, ethylene glycol dibutyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl ether, diethylene glycol diethylether, diethylene glycol mono-n-butyl ether, diethylene glycoldi-n-butyl ether, diethylene glycol mono-n-hexyl ether, ethoxytriglycol, tetraethylene glycol di-n-butyl ether, propylene glycolmonomethyl ether, propylene glycol monoethyl ether, propylene glycolmonopropyl ether, propylene glycol monobutyl ether, dipropylene glycolmonomethyl ether, dipropylene glycol monomethyl ether, tripropyleneglycol monomethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran andthe like; ester solvents such as diethyl carbonate, methyl acetate,ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate,i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate,n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate,methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzylacetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate,methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethylether acetate, ethylene glycol monoethyl ether acetate, diethyleneglycol monomethyl ether acetate, diethylene glycol monoethyl etheracetate, diethylene glycol mono-n-butyl ether acetate, propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate,propylene glycol monopropyl ether acetate, propylene glycol monobutylether acetate, dipropylene glycol monomethyl ether acetate, dipropyleneglycol monoethyl ether acetate, glycol diacetate, methoxytriglycolacetate, ethyl propionate, n-butyl propionate, i-amyl propionate,diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate,n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate,diethyl phthalate and the like; and nitrogen-containing solvents such asN-methylformamide, N,N-dimethylformamide, N,N-diethylformamide,acetamide, N-methylacetamide, N,N-dimethylacetamide,N-methylpropionamide, N-methylpyrrolidone and the like.

The solvents can be used singularly or in a combination of at least twokinds thereof.

The method of adding the respective components is arbitrary and an orderof addition is not particularly restricted. However, it is preferred toadd water in two divisions to alkoxysilane to control the hydrolysis anddehydrocondensation of alkoxysilane. When water is added for the firsttime, in order not to complete the hydrolysis and dehydrocondensation, aratio of water to alkoxyl groups of alkoxysilane (by mole ratio) may bein the range of 0.1 to 0.3 and preferably in the range of 0.2 to 0.25.When water is added for the second time, water may be arbitrarily added.However, the ratio of water to alkoxy groups of alkoxysilane (by moleratio) is preferably set in the range of 1 to 10. The time requiredbetween the first time addition of water and the second time addition ofwater, without restricting particularly, can be arbitrarily set. Anamount of a catalyst added may be in any range as far as it can promotethe reaction and the molar ratio of alkoxysilane to a catalyst ispreferably in the range of 1:0.1 to 0.001 by mole ratio. When a solventis employed for dilution, a ratio of dilution is in the range of 1 to100 times and preferably in the range of 3 to 20 times.

The alkoxysilane, catalyst and water, and a solvent as required areadded, followed by agitating for substantially several minutes to 5 hrto obtain a coating solution. The coating solution is coated on asubstrate to obtain a precursor of a dielectric thin film. When the kindof a solvent or alkoxysilane to be used is changed, the porosifyingconditions of a thin film can be controlled. When, by drying orcalcining, the solvent is evaporated or an alcohol component generatedby the hydrolysis is removed, pores are formed and thereby a dielectricthin film can be obtained.

As examples of methods for coating on a substrate, general methods suchas a spin coating method, a cast coating method, a dip coating methodand the like. In the case of the spin coating method, a substrate isplaced on a spinner, a sample is dropped on the substrate, the substrateis rotated at from 500 to 10,000 rpm, and thereby a dielectric thin filmhaving a uniform film thickness and excellent in the smoothness of thesurface thereof can be obtained.

When the solvent or an alcohol component generated by the hydrolysis ofalkoxysilane is dried and calcined to remove, the drying conditions arenot particularly restricted, and any condition is available as far asthe solvent or alcohol component can be evaporated. The calciningconditions are neither particularly restricted, and any condition isavailable as far as the condensation of a silanol group in a thin filmaccording to the calcination can be further promoted. Accordingly, thecalcination may be carried out in an atmosphere of any one of air, inertgas and vacuum. However, when H or a methyl group is present in the thinfilm, a temperature where these are not decomposed is required for thecalcination. Specifically, the calcination is desirably carried out at atemperature in the range of 250 to 450° C. in a nitrogen atmosphere.

Furthermore, the solvent and the alcohol component generated by thehydrolysis of alkoxysilane can be removed as well by use of an organicsolvent small in the surface tension or a supercritical fluid. Inparticular, the removal by the supercritical fluid that has no surfacetension when pressure and temperature are regulated is preferablebecause pores of the thin film are not broken and a highly porous filmcan be obtained.

In such a manufacturing method, the dielectric thin film can be obtainedin a state where it is in a self-supporting state or fastened to asubstrate. Pores of the obtained thin film can be confirmed to have theaverage pore diameter in the range of 0.5 to 10 nm by cross sectionalTEM observation of the thin film or measurement of the pore sizedistribution. Furthermore, a thickness of the thin film is, thoughdifferent depending on the manufacturing conditions, in the range ofsubstantially in the range of 0.05 to 2 μm.

(2) Thin Film That is Porosified by Self-Agglomeration of Silica Sol andOrganic Compound When Forming Film with Alkoxysilane by Sol-Gel Methodand Removing the Organic Compound After Forming a Film

A porous thin film that is obtained due to self-agglomeration of silicasol and an organic compound when a film is formed from alkoxysilane by asol gel method and the organic compound is removed after forming a filmcan be obtained from a coating solution in which, in the production of athin film (1), in a process for preparing a coating solution withalkoxysilane, as a pore forming agent (a mold), for example, an organiccompound such as a surface active agent is further added.

As the aforementioned surface active agent, usually a compound having along-chain alkyl group and a hydrophilic group can be used. Thelong-chain alkyl group is preferably one having 8 to 24 carbon atoms andfurther preferably one having 12 to 18 carbon atoms. Furthermore,examples of the hydrophilic groups include a group of quaternaryammonium salt, an amino group, a nitroso group, a hydroxyl group, acarboxyl group and the like. Among these, a group of quaternary ammoniumsalt or a hydroxyl group is preferable.

Specifically, as such a surface active agent, an alkylammonium saltrepresented by a general formula below:

C_(n)H_(2n+1)(N(CH₃)₂(CH₂)_(m))_(a)(CH₂)_(b)N(CH₃)₂C_(L)H_(2L+1)X_(1+a)

(In the formula, a is an integer between 0 and 2; b is an integerbetween 0 and 4; n is an integer between 8 and 24; m is an integerbetween 0 and 12; L is an integer between 1 and 24; and X is a halideion, HSO₄ ⁻ or a monovalent organic anion.) can be preferably used.

The surface active agent represented by the aforementioned generalformula forms micelles in a coating solution to be regularly arranged.In the invention, the micelle acts as a mold to form a complex fromsilica obtained by the hydrolysis and dehydrocondensation ofalkoxysilane and a surface active agent. Then, by removing the surfaceactive agent of the mold, a porous dielectric thin film having uniformpores regularly arranged can be prepared.

Furthermore, as the surface active agent, a compound having apolyalkylene oxide structure can be used as well. Examples of thepolyalkylene oxide structures include a polyethylene oxide structure, apolypropylene oxide structure, a polytetramethylene oxide structure, apolybutylene oxide structure and the like.

Specific examples of compounds having the polyalkylene oxide structurespecifically include ether type compounds such as polyoxyethylenepolyoxypropylene block copolymer, polyoxyethylene polyoxybutylene blockcopolymer, polyoxyethylene polyoxypropylene alkyl ether, polyethylenealkyl ether, polyoxyethylene alkyl phenyl ether and the like; and etherester type compounds such as polyoxyethylene glycerin fatty acid ester,polyoxyethylene sorbitan fatty acid ester, polyethylene sorbitol fattyacid ester, sorbitan fatty acid ester, propylene glycol fatty acidester, sucrose fatty acid ester and the like.

In the invention, the surface active agents can be used singularly or ina combination of at least two kinds selected therefrom.

An addition ratio of alkoxysilane, a catalyst and water is the same asthe aforementioned method (1). However, an addition amount of thesurface active agent is preferably in the range of 0.002 to 0.6 timesand more preferably in the range of 0.005 to 0.15 times based on themolar ratio of the alkoxysilane. The surface active agent may be addedin any state of a solid, a liquid and a solution obtained by dissolvingthe surface active agent in a solvent, without restricting to particularone.

By changing the combination between the surface active agent andalkoxysilane, the molar ratio therebetween or the like, according to theforegoing method (2), a dielectric thin film having a periodic porestructure such as a 2D-hexagonal structure, a 3D-hexagonal structure, acubic structure or the like can be manufactured.

In order to obtain such a dielectric thin film, the coating solutionobtained according to the method as mentioned above, similarly to theforegoing method (1), may be coated on a substrate followed by drying,further followed by calcining or extracting with an organic solvent toremove the surface active agent. Pores of the thus-obtained dielectricthin film can be confirmed to have the average pore diameter in therange of 1 to 10 nm by cross sectional TEM observation of a thin film orthe measurement of pore size distribution. Furthermore, when the porousthin film has a periodic pore structure such as a 2D-hexagonalstructure, a 3D-hexagonal structure, a cubic structure or the like, adiffraction peak having an interplanar spacing in the range of 1.3 to 13nm can be confirmed by the X-ray diffractometry (CuKα).

When the thus-obtained dielectric thin film has pores

of a cubic structure and particularly has a pore narrow part having aspacing from 1 to 40 Å between the pore walls in a pore and preferablyfrom 2 to 25 Å, the pore narrow part can be easily closed by themodification treatment to be described later so that a dielectric thinfilm in which the pore narrow part is at least partially closed can beobtained. The measurement of a magnitude of such a pore narrow part canbe confirmed by the electron beam structure analysis. The thus-obtaineddielectric thin film is excellent in the hydrophobicity. Furthermore,when it is used for a semiconductor material, a dielectric thin filmthat can inhibit a barrier metal from diffusing can be formed.

The dielectric thin film having such a pore narrow part can be formed aswell in a dielectric thin film having a 2D-hexagonal structure or a3D-hexagonal structure in which a narrow part is formed in a pore, inaddition to a dielectric thin film having a cubic structure.

For instance, a coating solution is prepared by partial hydrolysis anddehydrocondensation of alkoxysilane in the presence of a surface activeagent and silicon oil. In this case, it is preferable that a mixedsolution is prepared by mixing a surface active agent with silicon oilin advance and the resulting mixture is added to alkoxysilane that ispartially hydrolyzed and dehydrocondensed. Here, the term “beingpartially hydrolyzed and dehydrocondensed” means a state where the mixedsolution is fluidized without being gelated. In general, when theviscosity exceeds 105 poise, a solution is viewed as gelated.Accordingly, the solution has not the viscosity more than the foregoingviscosity.

It is considered that, when a coating solution is prepared in thismanner, a surface active agent is arranged with silicon oil at a centerto form a micelle. Then, it is considered that, when the coatingsolution is coated on a substrate, followed by drying, further followedby calcining to remove the surface active agent, the silicon oilconfined in the center of micelle remains in a state attached to thesurface inside of a pore of the dielectric thin film to form theaforementioned narrow part.

The foregoing silicon oil include, without particularly restricting,organic silicon compounds having polydimethylsiloxane as a maincomponent. Examples of such compounds include trimethylsiloxy-terminatedpolydimethylsiloxane, a copolymer of polyphenylsiloxane andpolydimethylsiloxane, a copolymer of polyphenylmethylsiloxane andpolydimethylsiloxane, a copolymer ofpoly-3,3,3-trifluoropropylmethylsiloxane and polydimethylsiloxane, acopolymer of polyethylene oxide and polydimethylsiloxane, a copolymer ofpolypropylene oxide and polydimethylsiloxane, a copolymer ofpolyethylene oxide, polypropylene oxide and polydimethylsiloxane,hydride-terminated polydimethylsiloxane, a copolymer ofpolymethylhydridesiloxane and polydimethylsiloxane, silanol-terminatedpolydimethylsiloxane and the like.

The silicon oil used in the present invention can be used singularly orin a combination of at least two kinds selected from the foregoingcompounds.

An amount of the silicon oil added is preferably in the range of 1 to100 parts by weight and more preferably in the range of 5 to 50 parts byweight, based on 100 parts by weight of the alkoxysilane. When theamount of the silicon oil added is set within the aforementioned range,a dielectric thin film in which a narrow part is formed in a pore can beeasily prepared.

In the dielectric thin film in which at least a part of the pore narrowpart is closed, the fact that the pore narrow part is closed andimprovement of the hydrophobicity can be confirmed by the measurement ofdielectric constant and cross sectional TEM observation of a thin film,which will be described later.

(3) Thin Film that is Porosified by Crystal Growth of Zeolite on Surfaceof Substrate

A thin film that is porosified can be obtained as well by crystal growthof zeolite on a surface of a substrate. The manufacturing method thereofis not particularly restricted. However, specifically, for instance, thefollowing methods can be cited.

(A) A coating solution containing crystallites of zeolite obtained byhydrothermal synthesis of a silica source such as alkoxysilane,colloidal silica or the like and with organic amine as a mold is coatedon a substrate, followed by drying and calcining to manufacture.

(B) A surface active agent is added to a coating solution containingcrystallites of zeolite obtained by hydrothermal synthesis of a silicasource of alkoxysilane, colloidal silica or the like and with organicamine as a mold, followed by coating on a substrate, further followed bydrying and calcining to prepare.

(C) In hydrothermal synthesis with alkoxysilane, colloidal silica or thelike as a silica source and with organic amine as a mold, a substrate isinserted to grow crystallites of zeolite on a surface of the substrate,followed by drying and calcining to prepare.

(D) A substrate coated with silica gel is subjected to zeolitecrystallization in aqueous vapor containing an organic amine, followedby drying and calcining to prepare (dry gel conversion).

As the organic amines which can be used for the foregoing preparation,tetrapropylammonium hydroxide, tetraethylammonium hydroxide,tetrabutylammonium hydroxide, tetrapentylammonium hydroxide,tripropylamine, triethylamine, triethanolamine, piperidine,cyclohexylamine, neopentylamine, isopropylamine, t-butylamine,2-methylpyridine, N,N′-dimethylbenzylamine, N,N-diethylethanolamine,di(n-butyl)amine, di(n-pentyl)amine, dicyclohexylamine,N,N-dimethylethanolamine, cholin, N,N-dimethylpiperazine,1,4-diazabicyclo(2,2,2)octane, N-methyldiethanolamine,N-methylethanolamine, N-methylpiperidine, quinuclidine,N,N′-dimethyl-1,4-diazabicyclo(2,2,2)octane dihydroxide,ethylenediamine, 2-imidazolidone and the like can be cited.

The obtained dielectric thin films can be confirmed to have a zeolitestructure from the diffraction peak obtained by the X-ray diffractometry(CuKα).

INDUSTRIAL APPLICABILITY

As mentioned above, according to the invention, a low dielectricconstant insulating film excellent in the controllability and high inthe mechanical strength can be readily obtained. The low dielectricconstant insulating film can be applied as well to high-speed devicesincluding various kinds of semiconductor devices that use silicon anddevices that use a compound semiconductor such as HEMT, high frequencydevices such as microwave ICs, MFMIS type high integration ferroelectricmemories, microwave transmission line or multi-layered wiring substratesthat use a film carrier and the like.

1-18. (canceled)
 19. A semiconductor device, comprising: a dielectricthin film having contact pores formed by using a method comprising: astep of forming a dielectric thin film in which a plurality of pores arearranged around a skeleton mainly made of a Si—O bond, on a surface of asemiconductor substrate on which a desired element region is formed; astep of applying patterning on a surface of the dielectric thin filmthrough a mask; and a step of bringing a gas containing at least onekind of tetramethylcyclotetrasiloxane (TMCTS), hexamethylsilazane (HMDS)and trimethylchlorosilane (TMCS) molecules into contact with thepatterned surface of the dielectric thin film; and a conductive filmfilled in the contact pores.
 20. The semiconductor device according toclaim 19, wherein the conductive film filled in the contact pores of thedielectric thin film formed on a surface of a semiconductor substrate isformed so as to come into contact with the semiconductor substrate. 21.The semiconductor device according to claim 20, wherein the dielectricthin film is a porous silica thin film, and a copper thin film formedinside the contact pores constitutes a wiring layer.
 22. Thesemiconductor device according to claim 21, wherein the porous silicathin film has a thickness of 0.05 to 2 μm.
 23. The semiconductor deviceaccording to claim 21, wherein the porous silica thin film has finepores having a cubic structure, and at least a part of the fine pores isclosed.
 24. The semiconductor device according to claim 23, wherein thefine pores are formed so as to have a wall distance of 0.2 to 2.5 nm.